Setting a default value for a field in a formset in Django

In a formset in Django, how do we set a default value for a field which needs a value from the http session? Since a session is required to get the value, we cannot set a default value in the model class itself. And I am not able to understand how to explicitly set the value in each form in the formset before saving in the view fu开发者_如何学Pythonnction.

Setting the initial attribute in the construction of the FormSet would work but for whatever reason, I get a compilation error. The code is like this:

formset = LineItemsInlineFormSet(initial=[{'updated_by':'user'}])

The compilation error is: init() got an unexpected keyword argument 'initial'

I am using Django 1.1.1

Any insight will be appreciated. Thanks in Advance.

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The idiom to instance a formset with initial data is:

data = {
     'form-TOTAL_FORMS': u'2',
     'form-INITIAL_FORMS': u'0',
     'form-MAX_NUM_FORMS': u'',
     'form-0-updated_by': u'user',
     'form-1-updated_by': u'user',
}

formset = LineItemsInlineFormSet(data)

Update:

As Jonny Buchanan noted, this approach gives you a bound formset, which will display validation errors if all required data is not provided. If it is not what you want, create your formset passing a custom Form with desired settings to django.forms.formsets.formset_factory().

It is common to set updated_by as the current logged-in user automagically upon update. If this is what you want:

1. omit the updated_by field in the form;
2. save() with commit=False if it is a ModelFormset;
3. set updated_by to current user; and
4. save object instances, now with the default commit=True.

In the admin site there is a convenient way to do this with inlines: overrride ModelAdmin.save_formset.